Resistance compound.



WILLIAM E. GARDNER, OF PITTSBURG, PENNSYLVANIA RESISTANCE coairouma.

No Drawing.

, to the passage of an electric current therethrough, as well as be)ractically indestruc tible by the heating e ect of the current.Thecompound consists of the following ingredients: lamp black, bone ash,andflour of mica. The lamp black, commonly termed soot, is of itself agood conductor of electric current, while bone ash is considered aspractically a non-conductor, and flour of mica as an absolutenon-conductor.

\Vhen thoroughly mixed, the conductivity of the compound, or theresistance ofl'ered thereby to the passage of an electric current, willdepend upon the proportion of'one element to the other, or others, whichproportions will depend upon the circumstance under which it isemployed.

Specification of Letters Patent. Application filed. October 6,1910.Serial Ii'o. 585,595.

Patented May 9,1911.

6 For most purposes, the lamp black and bone ash are to be p eferred,without the addition of the flour of mica, or the flour of micasubstituted for the bone ash.

All of the ingredients of the compound being practically infusible willpermit of its being raised to a very high degree of temperature, by anelectric current, particularly where it be desired to employ the samefor heating purposes, when properly proportioned.

I claim: l. The herein described compound, containing lamp black, andbone ash, for the purpose set forth.

2. The herein described compound, conthe purpose set forth.

3. The herein described compound, consisting of lamp black, bone ash,and flour of mica, for the purpose set forth.

In testimony whereof, I afiix my signature, in presence of two itnesses.

WILLIAM E. GARDNER.

taining lamp black. and flour of mica, for

\Vitnesses:

D. B. OAKS, R. S. HARRISON.

